There are great expectations for solar cells as clean energy sources, whereas further reduction of cost is necessary to attempt extensive diffusion. For this purpose, a thin film formation apparatus capable of uniform deposition of high quality amorphous silicon (hereafter “a-Si”) thin film on larger substrates is desired.
Moreover, a tandem structure solar cell, where a-Si solar cell is stacked on microcrystalline silicon (hereafter, “μc-Si”) solar cell, gives higher conversion efficiency than a-Si used individually. Therefore, a thin film formation apparatus for the deposition of μc-Si thin film is also desired.
As an art of thin film formation apparatus, Japanese unexamined patent publication No. S59-014633 discloses an art of a capacitively-coupled parallel plate type plasma CVD apparatus.